Keyless printing press

Abstract

The known keyless printing press including an ink feeder section consisting of an ink source roller, a transfer roller, a doctor roller, an anti-hysteresis doctor disposed on the circumferential surface of the doctor roller and the like, and also provided with a wetting device for a plate drum, is improved in order to realize a fresh condition of the ink source roller which is free from residual ink before printing ink having a uniform moisture content is applied thereto. The improvements reside in that a refresh doctor is disposed on the ink source roller at a position downstream of the nip between the ink source roller and the transfer roller for scraping residual ink from the circumferential surface of the ink source roller.

We claim: 
     
       1. A keyless printing press comprising an ink feeder section having an ink source roller, a transfer roller and a doctor roller rotatably supported in the press in contact with one another for sequentially transferring ink along the circumferential outer surfaces thereof, an ink delivery nozzle opposite said ink source roller for directing a spray of ink over the width of said ink source roller at a location at the circumferential outer surface of said ink source roller, an anti-hysteresis doctor engaging said doctor roller for scraping surplus ink from the circumferential outer surface of the doctor roller, a wetting device in operative association with said doctor roller for supplying wetting water to the doctor roller, and a refresh doctor engaging said ink source roller over the width thereof at a location, as taken in the direction of rotation of the ink source roller in the press, between the location at which said ink source roller contacts and transfer roller and the location at which said ink source roller is sprayed with ink directed by said ink delivery nozzle for scraping residual ink from the circumferential outer surface of said ink source roller over the width thereof. 
     
     
       2. A keyless printing press as claimed in claim 1, wherein said refresh doctor is disposed immediately upstream of said ink delivery nozzle with respect to the direction of rotation of said ink source roller in the press. 
     
     
       3. A keyless printing press as claimed in claim 1, wherein said ink delivery nozzle defines an ink delivery port therein through which ink is discharged from the nozzle toward said ink source roller, and said refresh doctor is disposed immediately upstream of said ink delivery port with respect to the direction of rotation of said ink source roller in the press. 
     
     
       4. In a keyless printing press including an ink feeder section having an ink source roller, a transfer roller and a doctor roller rotatably supported in the press in contact with one another for sequentially transferring ink along the circumferential surfaces thereof, an ink delivery nozzle opposite and ink source roller for directing a spray of ink over the width of the ink source roller at a location at the circumferential outer surface of the ink source roller, an anti-hysteresis doctor engaging the doctor roller for scraping surplus ink from the circumferential outer surface of the doctor roller, and a wetting device in operative association with the doctor roller for supplying wetting water to the doctor roller, the improvement comprising a refresh doctor engaging said ink source roller over the width thereof at a location between, as taken in the direction of rotation of the ink source roller in the press, the location at which said ink source roller in the press, the location at which said ink source roller contacts said transfer roller and the location at which said ink source roller is sprayed with ink directed by said ink delivery nozzle for scraping residual ink from the circumferential outer surface of said ink source roller over the width thereof so as to prevent differences in the proportion or amount of ink from arising along the width of said ink transfer roller. 
     
     
       5. The improvement in a keyless printing press as claimed in claim 4, wherein said refresh doctor is disposed immediately upstream of said ink delivery nozzle with respect to the direction of rotation of said ink source roller in the press. 
     
     
       6. The improvement in a keyless printing press as claimed in claim 4, wherein said ink delivery nozzle defines an ink delivery port therein through which ink is discharged from the nozzle toward said ink source roller, and said refresh doctor is disposed immediately upstream of said ink delivery port with respect to the direction of rotation of said ink source roller in the press.